A very large number of known embodiments of spacers exists, which is due to the fact that, in spite of their simple design, the spacers in many respects have to fulfill very heavy demands. The spacer must have a low flow resistance with respect to the coolant flowing through the fuel assembly along the fuel rods, and good resilient properties. The influence of the spacer on the neutron flux in the fuel assembly is also of considerable importance. It is difficult to find a material which at the same time has good resilient properties and little influence on the neutron flux, since almost all materials which have a small influence on the neutron flux also have poor resilient properties and therefore are not suitable for use in a spacer.